The MPLS technique, as a key technique in Next Generation Network, has been playing a more and more important role in IP networks. At the beginning, the MPLS technique was put forward to increase the forwarding speed of routers; however, it has been widely applied in the fields of traffic engineering, Virtual Private network (VPN) and Quality of Service (QoS) because of its inherent advantages and is becoming an important standard in large scale IP networks.
In the MPLS network, a label switching is used to forward data packets, and thus the routing of network may be controlled flexibly. The Forwarding path of data packet, in the MPLS network, is called Label Switched Path (LSP). The LSP is defined by the switching of label value, and the label value of data packet is switched at Label Switching Routers (LSRs) which may include an Ingress LSR and an Egress LSR.
In the MPLS network, it has become a pressing issue to detect failures and implement protection switching, as the MPLS technique has become a key technique for IP network multi-service bearer. Protection switching enhances the reliability and availability performance of MPLS networks. The protection switching implies that both routing and resources are pre-calculated and allocated to a dedicated protection LSP prior to failures of a working LSP. The protection switching therefore offers a strong assurance of being able to re-obtain the required network resources when the LSP connectivity is defected or interrupted.
FIG. 1 is a flow chart illustrating the protection switching in MPLS network in an existing art. As shown in FIG. 1, the method includes the following steps of:
Step 101: an Ingress LSR transmitting periodically probe packets via an LSP to an Egress LSR.
Step 102: if the Egress LSR does not receive the probe packets within pre-determined times, determining that the LSP is failed; the Egress LSR then transmitting a Backward Defect Indication (BDI) message to the Ingress LSR via a reverse path, to notify the Ingress LSR the failure of the LSP.
Step 103: upon receiving the BDI message, the Ingress LSR switching the working traffic to a protection LSP.
FIG. 2 is a schematic diagram illustrating the protection switching in the MPLS network in the existing art. As shown in FIG. 2, in a normal condition, the working traffic is distributed to the working LSP. The Egress LSR, if not receiving the probe packets within pre-determined times, transmits the BDI message to the Ingress LSR via a reverse path. Upon receiving the BDI message, the Ingress LSR switches the working traffic to the protection LSP.
In the existing art, the Ingress LSR determines that the LSP has been failed while receiving the BDI message, and correspondingly switches the working traffic. However, when a failure of the Egress LSR occurs, if a failure of the working LSP occurs, the Egress LSR is likely unable to transmit the BDI message to the Ingress LSR. The Ingress LSR thus may not switch the working traffic, as it may not learn that a failure of the working LSP occurs.
Furthermore, the Ingress LSR may not switch the working traffic when a failure of the Egress LSR occurs in the existing art, since the failed Egress LSR couldn't notify the Ingress LSR the failure in time. Consequently, the working LSP and protection LSP may only be terminated at the same Egress LSR limitedly. That is, the Ingress LSR is failed to terminate the working LSP and protection LSP at different Egress LSRs, as the Ingress LSR can not learn the working status of the Egress LSR, thereby reducing the security of the MPLS network.